From these duties COY'S HORSE were soon relieved to engage in military operations in Ireland, which country had become the theatre of intestine war. The Papists were in arms in favour of King James, who had arrived in Ireland with a body of troops from France; and, following that system of cruelty which has invariably been practised when religion has been the subject of contention, the hapless Protestants, being the weaker party, had been made to feel the full weight of Catholic vengeance. Many of the Protestants, particularly in Inniskilling and Londonderry, had taken arms. King William sent a body of troops under Duke Schomberg to their aid, and COY'S HORSE embarked at Highlake, in Cheshire, in the middle of August, 1689, for the same service. After landing at Belfast, the regiment was employed in covering the siege of _Carrickfergus_, and had its post in the lines before the town. This place having surrendered on the 28th of August, a detachment of the regiment, commanded by Captain Sir William Russel, escorted the garrison, consisting of two regiments of foot, "all stout fellows, but ill clothed," the first stage from the town; and such cruelties had been practised by the Papists, that, according to Story, who was an eye-witness, the troopers experienced some difficulty in preserving the Catholic soldiers from being torn to pieces by the country people, who were stimulated to revenge by the remembrance of past injuries. The regiment afterwards advanced with the army towards Newry, where a party of the enemy was assembled, who, on the approach of the English, set fire to the town, and retreated over the mountains to Dundalk. The English passed the mountains on the following day, when the enemy quitted Dundalk and retired to Atherdee, where the main body of King James's army was assembled. Marshal Duke Schomberg, finding Dundalk to be a strong situation, with a convenient harbour for obtaining supplies from England, and knowing that the enemy's army was more than double his own in numbers, formed an intrenched camp, where he resolved to continue during the remainder of the campaign; but the ground where the troops were encamped being low, and the weather proving wet, this injudicious choice of situation proved so fatal to his army, that the infantry corps lost half their men from disease. COY'S HORSE remained at Dundalk upwards of a month, and afterwards proceeded to Carlingford for the convenience of forage. During the winter, detached parties had frequent encounters with the bands of armed Papists who prowled the country, committing every description of outrage; and an out-guard of the regiment, posted in the pass of Newry, was sharply engaged with a party of the enemy, who attempted to force the pass, but were repulsed with loss, the gallant English Cuirassiers proving more than a match for their antagonists. [Sidenote: 1690]